Within a joint cavity, cartilage is the smooth lining that covers the ends of bones where the bones meet to form the joint and that gives the joint freedom of movement by decreasing friction. The cartilage is kept slippery by synovial fluid, joint fluid made by the joint lining (the synovial membrane). The synovial fluid is contained in a soft tissue enclosure around the joints, called the joint capsule. The synovial fluid has a high content of hyaluronic acid (HA) which increases the viscosity of the synovial fluid. Normal synovial fluid contains 3-4 mg/ml of HA. Along with lubricin, HA is one main lubricating components of the synovial fluid.
If the articular cartilage degenerates or erodes, the concentration of HA decreases and the synovial fluid becomes less viscous. The underlying bone becomes uncovered resulting in bone-to-bone contact which causes significant pain. Additionally, as a result of this bone-to-bone contact, small outgrowths called bone spurs, or osteophytes, may form in the joint. Bits of bone or cartilage can break off and float inside the joint space causing more pain and damage.
Many factors may contribute to the development of a cavity or joint condition. They may include a prior injury to a component of the cavity including strains, rupture, dissection, partial and full tears of the lumen or lining of the cavity, ligaments, tendon, cartilages, meniscus or synovial lining. The cavity or joint may also be affected by an autoimmune disease such as a rheumatoid arthritis or a degenerative disease such as an osteoarthritis (OA).
Currently, there are no effective alternatives for treating joint diseases between a temporary pain relief and a surgical intervention. For example, OA affects approximately 21 million Americans a year accounting for 25% of visits to primary care physicians. It is estimated that 80% of the population will have radiographic evidence of OA by age 65 with more than 60% of those exhibiting symptoms. Most people with osteoarthritis use drug therapy to ease the symptoms of the disease. Majority of OA drugs focus mainly on relieving pain, and have little to no effect on slowing or reversing the breakdown of the cartilage. Another approach to treating osteoarthritis, specifically knee osteoarthritis, is an injection into the joint of hylauronic acid (“HA”). Similar to drug therapies, the HA injections provide temporary relief but do not effect the progression of the disease. Finally, if the above methods of OA management are ineffective, a surgical intervention such as total joint replacement is required.
Co-pending U.S. patent application Ser. No. 11/418,153 discloses compositions comprising PEG and magnesium for treatment of pain or inflammation in subjects. Co-pending U.S. patent application Ser. No. 11/418,152 discloses compositions comprising PEG and magnesium for treatment of neuronal injury in subjects.
Accordingly, there is a need for an effective therapy that will control or more preferably reverse the progression of a cavity pathology in addition to relieving pain.